The present invention relates to a disposable sensor for use in measuring respiration of a patient. In particular, the present invention relates to a respiratory inductive plethysmograph (xe2x80x9cRIPxe2x80x9d) disposable sensor formed from a flexible stretchable ribbon having a conductor secured thereto. The disposable sensor is cut to size by a health care provider sized to encircle a patient to measure respiration. The present invention also relates to a connector assembly for the disposable sensor that releasably grips the conductor of the sensor.
Respiratory inductive plethysmograph monitoring apparatus are used to measure and monitor the respiration of a patient. Typically, the RIP monitoring apparatus includes a conductive loop closely encircling a body member. The inductance of the conductive loop is a measure of the cross sectional area encircled. Changes in inductance reflect the respiration of the patient. The conductive loop is connected to an electronic monitoring device, which includes circuitry that reliably and accurately measures changes in the inductance of the conductive loop mounted on the body. Respiratory movements of the wearer result in changes in the cross-sectional areas and hence in the inductance of the conductive loop. Once these changes in inductance are converted to an electrical signal for the conductive loop, the signal is calibrated by the electronic monitoring device to accurately measure the volume of respiration. To ensure accurate monitoring of the patient""s respiration, it is important that the conductor loop fit snugly about the patient""s torso such that the expansions and contractions of the conductor closely follow the expansions and contractions of the chest and abdomen. Further, since it is impractical to render the conductors expandable, some other mechanism for accommodating expansion and contraction of the conductors must be employed.
U.S. Pat. No. 4,308,872 to Watson et al entitled xe2x80x9cMethod and Apparatus for Monitoring Respirationxe2x80x9d discloses an apparatus for monitoring respiration. In one embodiment, the monitoring apparatus includes a tubular stretch bandage in the form of a long sleeveless sweater worn closely fitted over the torso of a patient. A conductor is attached to the sweater in a number of turns around the torso from the lower abdomen to the upper chest, and so will provide a measure of area averaged over the entire torso. More turns may be placed over one portion of the torso and fewer over other portions, if it is desired to give greater weight to changes in area of one portion of the torso relative to others. The multi-turn loop is closed by a vertical section returning to the starting point. Both ends of the loop are electrically connected to an electronic circuit module, which is located on the patient""s lower side. In another embodiment, the monitoring apparatus includes two elastic tubes located about the upper chest and the lower abdomen of the patient. Conductors are mounted in a single turn loop circumferentially of tubes. Snap fasteners are provided for holding the band together.
U.S. Pat. No. 4,807,640 to Watson et al., entitled xe2x80x9cStretchable Band-Type Transducer Particularly Suited For Respiration Monitoring Apparatusxe2x80x9d discloses a monitoring apparatus having a conductor, which is supported on a strip of woven fabric securable about a patient""s torso. The fabric strip is stitched under tension by a plurality of longitudinally extending elastic stitches such that when the tension in the strip is released, the fabric becomes bunched or puckered along its entire length. An insulated wire conductor is stitched to one side of the fabric in a zigzag pattern. The stretching of the fabric in a longitudinal direction is accommodated by the puckers or folds with corresponding extension of the wire being accommodated by a widening and flattening of the saw tooth pattern. In use, the length of the band in its unstretched condition should be less than the circumference of the encircled portion of the torso of the patient such that the band may be stretched for a snug fit. To accommodate connection of the wire to the monitoring apparatus, the conductor is secured to the fabric such that both ends of the conductor terminate at the same longitudinal edge of the band. The ends of the conductor are soldered to connecting pins which are then secured in shrink tubing such that the tips of the connecting pins are exposed. The shrink tubing is stapled to the ends of the band. The conductors are then secured to a monitoring device.
The ""640 Patent also discloses a RIP monitoring apparatus having a stretchable band. The stretchable band includes a piece of nonwoven fabric, and a piece of tissue paper secured to the nonwoven fabric. A piece of elastic material is adhesively secured between the nonwoven fabric and the tissue paper along a substantial portion of the length. The elastic material in a stretched condition when the first and second pieces of material are in a flat condition. As described above, the nonwoven fabric and the tissue paper define crosswise puckers when the elastic material is in an unstretched condition for accommodating stretching of the band when the elastic material is stretched. A conductor is adhesively secured between the nonwoven fabric and the tissue paper. A fastener, such as, for example, a hook and loop fastener, is secured to the opposing ends of the band for securing the band to the patient. Free ends of the conductor extend from the ends of the band are connected to a LC oscillator circuit contained a housing secured to one end of the band. The LC oscillator circuit is then electrically connected to a monitoring apparatus.
None of these RIP monitoring apparatus, however, are suited for mass production. Each of these devices has a rather complex construction, which results in higher manufacturing costs and final product costs. Due to the expense, it is impractical to discard them after a single use. Yet in the medical field, where sanitary considerations are paramount for sound medical reasons as well as psychological ones, it is preferred to render disposable any apparatus that comes into contact with the patient, such as occurs with the RIP bands. Furthermore, these RIP monitoring apparatus are cut in predetermined lengths and can not be easily sized to fit individual users. Hospitals would need to maintain a substantial inventory of different sized RIP bands.
It is accordingly an object of the present invention to provide a RIP band sensor device which overcomes the aforementioned drawbacks.
It is therefore an object of the present invention to provide a low cost sensor device for monitoring a patient""s respiration that can be discarded after a single use.
It is another object of the present invention to provide a low cost RIP band sensor device that can be readily and easily sized to an individual.
It is another object of the present invention to provide a disposable sensor for monitoring the volume of an expandable organ during respiration.
It is a further object of the present invention to provide a RIP sensor device that can easily be connected to a monitoring apparatus.
It is yet a further object of the invention to provide a flexible RIP band that can be mass produced.
It is another object of the present invention to provide a connector assembly for a disposable sensor that establishes an electrical connections with a conductor wire in the disposable sensor.
Additional objects and advantages of the invention are set forth, in part, in the description which follows, and, in part, will be apparent to one of ordinary skill in the art from the description and/or practice of the invention.
In response to the foregoing challenges, applicants have developed an innovative disposable sensor for monitoring and measuring the respiration of a patient. The disposable sensor includes at least one flexible band adapted to encircle a portion (e.g., the chest or abdomen) of the patient. A conductor strip is secured to the ribbon. It is contemplated that the conductor strips extends in a zig-zag or other predetermined pattern on the ribbon.
In accordance with the present invention, it is contemplated that the stretchable ribbon may include a first flexible ribbon of an elastomeric material, a second flexible ribbon of an elastomeric material secured to the first flexible ribbon of elastomeric material, and a conductor strip located between the first and second flexible ribbon of elastomeric material. The conductor strip extends in a zig-zag or other predetermined pattern between the first and second ribbon. In accordance with the present invention, it is contemplated that the first and second flexible ribbons are formed from a woven material. The first and second flexible ribbons are also formed from a thermoplastic elastomer.
The disposable sensor also includes a connector assembly for connecting and securing a first free end of the ribbon to a second free end of the ribbon. The connector assembly is operatively coupled to the conductor strip, and is further adapted to be connected to a monitoring device. In operation, changes in inductance of the conductor strip are transmitted through the connector assembly to the monitoring device.
In accordance with the present invention, the connector assembly for the disposable sensor includes a compression assembly for mechanically compressing the conductor strip. It is contemplated that the conductor strip may include a conductive wire having an outer insulation layer. The compression assembly cuts away the outer insulation layer.
It is also contemplated that the connector assembly of the disposable sensor may include a first connector portion for releasably receiving the first free end of the flexible ribbon. The first connector portion is adapted to engage a portion of the conductor strip located adjacent the first free end. The connector assembly also includes a second connector portion for releasably receiving the second free end of the flexible ribbon. The second connector portion being adapted to engage a portion of the conductor strip located adjacent the second free end.
The present invention is also directed to a method of measuring and monitoring changes in volume of an expandable organ of a patient. By measuring the changes in volume, the respiration of a patient may be measured and monitored. The method includes providing a supply of a flexible disposable sensor ribbon, cutting a length of the flexible disposable sensor ribbon to encircle a torso of the patient, securing a first end of the length to a releasable connector assembly, securing a second end of the length the releasable connector assembly, connecting the releasable connector assembly to a monitoring assembly, and monitoring changes in inductance of the flexible disposable sensor ribbon to measure and monitor the changes in volume of an expandable organ of the patient. The method further includes disposing of the length of the flexible disposable sensor ribbon after monitoring changes in inductance of the flexible disposable sensor band.
The present invention is also directed to an assembly apparatus for assembling a disposable RIP sensor band. The assembly apparatus includes a first supply assembly for supplying a first flexible ribbon, a second supply assembly for supplying a second flexible ribbon, and a conductor strip supply assembly for supplying the conductor strip. The supplies are positioned such that the conductor strip is located between the first flexible ribbon and second flexible ribbon. The assembly apparatus further includes a movable feeding assembly for feeding the conductor strip between the first and second flexible ribbons in a predetermined pattern, and a fixing assembly for fixing the first flexible ribbon to the second flexible ribbon such the conductor strip is secured therebetween in the predetermined pattern.
In accordance with the present invention, the fixing assembly may include a pair of pressing cylinders for applying pressure to the first and second flexible bands to sandwich the conductor strip therebetween. It is further contemplated that the fixing assembly may bond the first and second flexible ribbons together. The ribbons may be bonded together using heat or sound waves.